scholarly journals A Statistical Evolution Model of Concrete Damage Induced by Seawater Corrosion

Materials ◽  
2021 ◽  
Vol 14 (4) ◽  
pp. 1007
Author(s):  
Hangjie Lv ◽  
Jiankang Chen ◽  
Chunsheng Lu
Keyword(s):  
Damage Evolution ◽  
Corrosion Damage ◽  
Evolution Model ◽  
Calcium Sulfoaluminate ◽  
Concrete Corrosion ◽  
Basic Law ◽  
Exponential Growth Model ◽  
Concrete Damage ◽  
Expansion Force ◽  
Statistical Evolution

The transmission of sulfate ions in concrete results in formation of calcium sulfoaluminate crystals due to chemical reactions. The expansion of calcium sulfoaluminate crystals is the main cause of concrete corrosion damage. In this study, ultrasonic analysis was used to detect the modulus change of concrete due to sulfate corrosion to obtain the basic law of corrosion damage evolution. An exponential growth model was developed for the internal expansion force based on the chemical reaction rate of calcium sulfoaluminate crystallization. Then, the evolution equation of the number density of microcracks was derived based on their initiation and balance conditions. Finally, a statistical model was developed for the concrete damage evolution by integrating the volume of microcracks. It is shown that the statistical evolution model can well characterize the evolution of concrete corrosion damage.

Analysis of Concrete Corrosion and Damage Mechanism under the Actions of Multiple Salts and Dry-Wet Cycles

2014 ◽  
Vol 578-579 ◽  
pp. 1477-1481
Author(s):  
Xiao Ping Su
Keyword(s):  
Chemical Composition ◽  
Energy Spectrum ◽  
Corrosion Damage ◽  
Damage Mechanism ◽  
Composition Analysis ◽  
Concrete Durability ◽  
Chemical Attack ◽  
Concrete Corrosion ◽  
Concrete Damage ◽  
Corrosion Mechanisms

On the basis of concrete durability experimental results under the actions of multiple salts and dry-wet cycles, the internal microstructures of concrete subjected to the corrosion damage are studied in this article. The EDX energy spectrum analysis and chemical composition determination are discussed, and the concrete corrosion mechanisms under the actions of multiple salts and dry-wet cycles are studied further. The results indicate that the internal microstructures of ordinary concrete and fly ash concrete in the multi-salt solution are loose and porous after dry-wet cycles. There are a lot of crystals gathering in the concrete cracks. Through the EDX energy spectrum and chemical composition analysis, the main composition in them is CaCO3, doping with a small amount of Na2SO4, Na2CO3, or NaHCO3, etc. While the internal structure of air-entraining concrete is not only relatively dense, but also corroded by multiple salts. Under the condition of dry-wet cycles, the concrete damage by salt corrosion is a complicated process which including both chemical attack and physical function, and the damage speed and degree to crystallization corrosion by salts is quicker and even more serious than that of the chemical erosion.

scholarly journals A Strain Rate-Dependent Damage Evolution Model for Concrete Based on Experimental Results

2021 ◽  
Vol 2021 ◽  
pp. 1-8
Author(s):  
Bin Xu ◽  
Xiaoyan Lei ◽  
P. Wang ◽  
Hui Song
Keyword(s):  
Strain Rate ◽  
Uniaxial Compression ◽  
Damage Evolution ◽  
Damage Model ◽  
Evolution Model ◽  
Experimental Results ◽  
Strain Rates ◽  
Compression Tests ◽  
Stress Strain ◽  
Actual Damage

There are various definitions of damage variables from the existing damage models. The calculated damage value by the current methods still could not well correspond to the actual damage value. Therefore, it is necessary to establish a damage evolution model corresponding to the actual damage evolution. In this paper, a strain rate-sensitive isotropic damage model for plain concrete is proposed to describe its nonlinear behavior. Cyclic uniaxial compression tests were conducted on concrete samples at three strain rates of 10−3s−1, 10−4s−1, and 10−5s−1, respectively, and ultrasonic wave measurements were made at specified strain values during the loading progress. A damage variable was defined using the secant and initial moduli, and concrete damage evolution was then studied using the experimental results of the cyclic uniaxial compression tests conducted at the different strain rates. A viscoelastic stress-strain relationship, which considered the proposed damage evolution model, was presented according to the principles of irreversible thermodynamics. The model results agreed well with the experiment and indicated that the proposed damage evolution model can accurately characterize the development of macroscopic mechanical weakening of concrete. A damage-coupled viscoelastic constitutive relationship of concrete was recommended. It was concluded that the model could not only characterize the stress-strain response of materials under one-dimensional compressive load but also truly reflect the degradation law of the macromechanical properties of materials. The proposed damage model will advance the understanding of the failure process of concrete materials.

Partitioned Cyclic Fatigue Damage Evolution Model for PB-Free Solder Materials

2007 ◽  
Author(s):  
Leila J. Ladani ◽  
A. Dasgupta
Keyword(s):  
Fatigue Damage ◽  
Creep Deformation ◽  
Damage Evolution ◽  
Evolution Model ◽  
Micro Scale ◽  
Elastic Plastic ◽  
Constitutive Properties ◽  
Free Solder ◽  
Cyclic Damage ◽  
Creep Deformations

This study presents an approach to predict the degree of material degradation and the resulting changes in constitutive properties during cyclic loading in viscoplastic materials in micro-scale applications. The objective in the modeling approach is to address the initiation and growth of distributed micro-damage, in the form of micro-cracks and micro-voids, as a result of cyclic, plastic and creep deformations of material. This study extends an existing micromechanics-based approach, developed for unified viscoplastic models [Wen, et al, 2001], which uses dislocation mechanics to predict damage due to distributed micro-scale fatigue crack initiation [Mura and Nakasone, 1990]. In the present study, the approach is extended to a partitioned viscoplastic framework, because the micro-scale mechanisms of deformation and damage are different for plastic and creep deformation. In this approach, the model constants for estimating cyclic damage evolution are allowed to be different for creep and plastic deformations. A partitioned viscoplastic constitutive model is coupled with an energy partitioning (E-P) damage model [Oyan and Dasgupta, 1992] to assess fatigue damage evolution due to cyclic elastic, plastic and creep deformations. Wen’s damage evolution model is extended to include damage evolution due to both plastic and creep deformations. The resulting progressive degradation of elastic, plastic and creep constitutive properties are continuously assessed and updated. The approach is implemented on a viscoplastic Pb-free solder. Dominant deformation modes in this material are dislocation slip for plasticity and diffusion-assisted dislocation climb/glide for creep. The material’s behavior shows a good correlation with the proposed damage evolution model. Damage evolution constants for plastic and creep deformation were obtained for this Pb-free solder from load drop data collected from the mechanical cycling experiments at different temperatures. The amount of cyclic damage is evaluated and compared with experiment.

A new ductile damage evolution model

1993 ◽  
Vol 60 (4) ◽  
pp. R73-R76
Author(s):  
S. Chandrakanth ◽  
P. C. Pandey
Keyword(s):  
Damage Evolution ◽  
Evolution Model ◽  
Ductile Damage

New damage evolution model of rock material

2020 ◽  
Vol 86 ◽  
pp. 207-224 ◽  
Author(s):  
Wei Gao ◽  
Xin Chen ◽  
Chengjie Hu ◽  
Cong Zhou ◽  
Shuang Cui
Keyword(s):  
Damage Evolution ◽  
Rock Material ◽  
Evolution Model

Damage Analysis for Quasi-Birttle Materials of CT Image under Uniaxial Compression

2010 ◽  
Vol 168-170 ◽  
pp. 373-379
Author(s):  
Cheng Yi ◽  
Hong Guang Zhu ◽  
Li Zhen Liu
Keyword(s):  
Density Distribution ◽  
Uniaxial Compression ◽  
Damage Evolution ◽  
Fractal Theory ◽  
Threshold Value ◽  
Damage Analysis ◽  
Ct Image ◽  
Segmentation Method ◽  
Material Density ◽  
Concrete Damage

In the damage research before on the CT image of quasi-brittle materials such as concrete, the damage evolution is often described by the change of average CT values or image threshold segmentation method. However, the evolution of average CT values is insensitive to the damage, and the threshold value is always not only, which grimly depends on the researchers’ judgment. Because CT image is a gray image and different grayscale expresses different density distribution, it is tried in the paper to express the variety of material density with variety of grayscale of CT image. A description index of Rd from fractal theory is introduced in the paper to describe the variety of grayscale. Thereby, a damage variable is defined by Rd index, which can be used to study the developing process and evolving rule of concrete damage.

Further Advances on Concrete Coating Impact on Pipeline Strength

2017 ◽  
Author(s):  
Alberto Battistini ◽  
Luca Catena ◽  
Adelina Mancini ◽  
Lorenzo Marchionni ◽  
Antonio Parrella ◽  
...  
Keyword(s):  
Mechanical Behavior ◽  
Damage Evolution ◽  
Bending Stiffness ◽  
The State ◽  
Fe Model ◽  
Deformation Capacity ◽  
Strain Concentration ◽  
Concrete Damage ◽  
Strength And Deformation ◽  
Concrete Coating

Concrete Weight Coating is used in offshore industry to provide for pipeline vertical and lateral stability against waves and currents and to guarantee protection against fishing activities. Reinforced concrete coating of adequate strength, especially in case of thick coatings for stringent in-place stability requirements, entails additional bending stiffness and consequently strain concentration at field joints, thus significantly affecting the state of stress and strain on the pipe steel during laying firstly, and then during operations. Attention of the offshore pipeline industry has been focused in the development of experimental and theoretical activities in a more scientific way, which aimed to satisfy the need of a better knowledge in this field. Both analytical and FEM solutions are available in the free literature and relevant standards to predict the contribution of concrete coating layer on global pipeline strength and deformation capacity and simplified threshold values for the concrete damage are provided, as well. Generally, for installation analysis purpose, a pipeline with equivalent mechanical behavior (bending moment-curvature relationship) and physical (weight) properties is used in installation and operation analyses. No assumptions are typically made on concrete damage evolution to evaluate the decay of pipe capacity beyond the elastic range. In this paper new advances in modelling the mechanical behavior of concrete coated joints are discussed. In particular an advanced ABAQUS finite element model is proposed to take into account the effect of concrete coating damage on the overall capacity. The following effects have been accounted: • Non-linear stress-strain relationship of the steel at large usage factors/curvatures on the strain concentration at the field joint. • Concrete coating damage evolution on global pipeline bending stiffness. In this paper: • The state-of-the-art about published materials, numerical studies and design approaches on concrete material modelling and concrete coated pipes is briefly presented; • A FEM based analysis methodology is drawn and proposed for the strength and deformation capacity assessment of a concrete coated pipe; • The FEM model is calibrated on available full scale tests; • The results of a project case study performed with ABAQUS FE Model are given.

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